Theriva Biologics, Inc.

APPENDIX A

Profit Corporation Certificate of Amendment (PURSUANT TO NRS 78.380, 78.385, 78.390) Certificate to Accompany Restated Articles or Amended and Restated Articles (PURSUANT TO NRS 78.403) Officer's Statement (PURSUANT TO NRS 80.030) TYPE OR PRINT - USE DARK INK ONLY - DO NOT HIGHLIGHT Page 1 of 2 Revised: 7/1/2026 1. Entity information: Name of entity as on file with the Nevada Secretary of State: Theriva Biologics, Inc. You must include the filing fee with this form. See the instructions for more information. Certificate to Accompany Restated Articles or Amended and Restated Articles X Certificate of Amendment to Articles of Incorporation - After Issuance of Stock (Pursuant to NRS 78.385 and 78.390) Certificate of Amendment to Articles of Incorporation - Before Issuance of Stock (Pursuant to NRS 78.380) Statutory statement: The signers are at least two-thirds of the incorporators or two-thirds of the board of directors, and as of the date of the certificate, the corporation has not issued any voting stock. 3. Amendment Filing Type: (Select only one box) Domestic Corporation If amending, complete sections 1, 3, 6 and 7. 2. Restated or Amended and Restated Articles: (Domestic corporations) If restating, complete sections 1, 2, and 7. If amending and restating, complete sections 1, 2, 3, 6 and 7. You must include the Restated Articles or the Amended and Restated Articles with this filing. Entity or Nevada Business Identification Number (NVID): E0776232008-6 Restated Articles: The articles are being restated without any changes and include all amendments made up to the date of this certificate. The certificate must be signed by an officer of the corporation. Statutory Statement: The officer signing this certificate confirms that they are authorized to do so by a board resolution adopted on the date listed, and that this certificate accurately reflects the articles of incorporation as amended as of that date. Date the board of directors adopted the resolution to approve the restated articles: Amended and Restated Articles: The articles are being restated to include all previous amendments and the current changes. Check this box if the amendment is for a name change only. • No stockholder approval is required for a name change under NRS 78.390(8). X If the amendment includes other changes, confirm the following: • The proposed amendment(s) were submitted to the stockholders for approval. • Stockholders holding at least a majority of the voting power (or greater, if required by the articles or law) approved the amendment(s). • Voting Results (e.g., number of shares for/against or percentage approved): 401 North Carson Street Carson City, Nevada 89701-4201 (775) 684-5708 Date:

Date: 5. Effective Date and Time: (Optional) 6. Describe the Applicable changes (select all that apply): Changes: The entity name has changed The registered agent has changed (attach Certificate of Acceptance from new registered agent) The entity’s purpose has changed The initial Board of Directors/ Trustees or Stockholders from the organization have changed IRS tax language added. The organization changed the articles The organization deleted articles The authorized shares have been amended Other (attach additional page[s] if necessary) 7. Signature: (Required) You must include the filing fee with this form. See the instructions for more information. Page 2 of 2 Revised: 7/1/2026 Profit Corporation Certificate of Amendment (PURSUANT TO NRS 78.38, 78.385, 78.390) Certificate to Accompany Restated Articles or Amended and Restated Articles (PURSUANT TO NRS 78.403) Officer's Statement (PURSUANT TO NRS 80.030) 401 North Carson Street Carson City, Nevada 89701-4201 (775) 684-5708 4. Officer's Statement Name used in the home state (if different from the name used in Nevada): : Foreign corporations only. Complete 1, 4, 6 and 7. Title Print First Name X _____________________________________________ Signature i Print Last Name Steven A. Shallcross Jurisdiction of formation (state or country): Attach a certified copy or certificate showing that amendments were filed in the state where the corporation was formed. Attach additional page(s) if additional signatures are necessary. The organization amended the articles as follows: (provide article numbers, if available) See attached Appendix A. Effective date is not to exceed 90 days of the filing date of this form. If left blank, this form will be effective upon filing with the SOS. If you select a later effective date but the effective time is left blank, the effective time will be at 12:01 Pacific time on the specified date. Time:

Appendix A The first sentence of the first paragraph of Article 3 shall be amended to read as follows: The total number of shares of all classes of stock that the Corporation shall have authority to issue is Five Hundred Ten Million (510,000,000) shares consisting of: Five Hundred Million (500,000,000) shares of common stock, $0.001 par value per share ("Common Stock"); and Ten Million (10,000,000) shares of preferred stock, $0.001 par value per share ("Preferred Stock"). The remaining provisions of Article 3 shall remain the same.

Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. T04838-Z94085 For Against Abstain ! ! ! ! ! ! THERIVA BIOLOGICS, INC. The Board of Directors recommends you vote FOR Proposals 1, 2 and 3: Note: To transact such other business as may properly come before the meeting or any adjournments or postponements of the meeting. 1. To approve an amendment to the Company’s Articles of Incorporation, as amended (the "Articles of Incorporation"), to, at the discretion of the Company’s Board of Directors (the "Board"), effect an increase in the number of authorized shares of common stock, $0.001 par value per share (the "Common Stock"), to 500,000,000 shares (the "Authorized Common Stock Increase Proposal"), such amendment to be effected after stockholder approval thereof only in the event the Board still deems it advisable. 2. To ratify and confirm the prior approval obtained at the Company’s 2026 Annual Meeting of Stockholders and, to the extent necessary, to grant a new approval, in each case pursuant to Section 713(a) of the NYSE American Company Guide and the terms of an inducement agreement, of the issuance of up to an aggregate of 16,184,560 shares of Common Stock upon the exercise of the Company’s common stock purchase warrants issued to institutional investors in the Company’s private placement offering, which closed on October 17, 2025 (the "Warrant Exercise Proposal"). 3. To approve a proposal to adjourn the Special Meeting to a later date, if necessary or appropriate, to permit further solicitation and vote of proxies in the event that there are insufficient votes for, or otherwise in connection with, the approval of the Authorized Common Stock Increase Proposal and/or the Warrant Exercise Proposal. Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name by authorized officer. ! ! ! SCAN TO VIEW MATERIALS & VOTEw THERIVA BIOLOGICS, INC. 9605 MEDICAL CENTER DRIVE, SUITE 270 ROCKVILLE, MARYLAND 20850 VOTE BY INTERNET - www.proxyvote.com or scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information up until 11:59 p.m. Eastern Time the day before the meeting date. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. ELECTRONIC DELIVERY OF FUTURE PROXY MATERIALS If you would like to reduce the costs incurred by our company in mailing proxy materials, you can consent to receiving all future proxy statements, proxy cards and annual reports electronically via e-mail or the Internet. To sign up for electronic delivery, please follow the instructions above to vote using the Internet and, when prompted, indicate that you agree to receive or access proxy materials electronically in future years. VOTE BY PHONE - 1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions up until 11:59 p.m. Eastern Time the day before the meeting date. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717.

T04839-Z94085 Important Notice Regarding the Availability of Proxy Materials for the Special Meeting: The Notice of Meeting, Proxy Statement and Proxy Card are available at www.proxyvote.com. THERIVA BIOLOGICS, INC. SPECIAL MEETING OF STOCKHOLDERS NOVEMBER 18, 2026, AT 3:30 P.M. (LOCAL TIME) THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS The undersigned stockholder hereby appoints Steven A. Shallcross as proxy, with the power to appoint his substitute, and hereby authorizes him to represent and to vote, as designated on the reverse side of this ballot, all of the shares of common stock of THERIVA BIOLOGICS, INC. that the undersigned is entitled to vote at the Special Meeting of Stockholders to be held at 3:30 p.m. (local time) on November 18, 2026, at the Company’s principal place of business for research and clinical development, located at Carrer Torrent de Can Ninou, naus 5-6, 08150 - Parets del Vallès (Barcelona) Spain, or any adjournment or postponement thereof. This proxy, when properly executed, will be voted in the manner directed herein. If no such direction is made, this proxy will be voted in accordance with the Board of Directors’ recommendations. Continued and to be signed on reverse side